Operating mechanism



July 1, 1947. c. w. WANDREY 2,423,275

' OPERATING MECHANISMS Filed Sept. 14, 1942 l aljmllllmlllIIIIMINH"MNl"Illllllllllllllllllll!!! FIGJ CLARENCE w WANDREY Q AM HIS ATTORNEY Patented July 1, 1947 OPERATING MECHANISM Clarence W. Wandrey, Elmwood Park, 111., assignor to Zenith Radio Corporation, a corporation of Illinois Application September 14, 1942, Serial No. 458,294 8 Claims. (01. 171-242) My invention relates to operating mechanisms, and more particularly to mechanisms for mov ing a member longitudinally along a track or guide.

In the manufacture of radio receivers it is common to provide adjustably tuned circuits in which the inductance is adjustable by moving a powdered iron core into and out of the inductance coll. Such powdered iron cores are generally made cylindrical in shape, small in diameter, and of a length comparable to the length of the inductance coil. Tubular guides of paper or similar material are usually provided within the inductance coil, of sufllcient inside diameter to accommodate the powdered iron core for sliding motion within the coil.

Due to manufacturing inaccuracies the driving mechanism for such core is desirably at tached to the core by flexible means. Such flexible means between the driving mechanism and the core prevents binding of the core, which might otherwise be caused by the action of the driving mechanism in forcing the core in 'a direction different from that imposed on the core by the cylindrical guide within the inductance coil.

It is an object of my invention to provide a new and improved flexible means for driving such a powdered iron core.

It is also an object of my invention to provide such means so arranged that the shock of repeated use is not eifective to distort the driving means and destroy its reset accuracy.

It is a further object of my invention to provide such flexible means which is cheap, easy of manufacture and assembly with the driving mechanism and core, and which is yet rugged and provides for easy adjustment.

Thefeatures of my invention which I believe to be novel are set forth with particularity in the appended claims. My invention itself, both as to its organization and manner of operation, together with further objects and advantages thereances are connected, is described and claimed in of may best be understood by reference to the selectable adjustable stops I4 and I5. This arrangement of the three adjustable inductances III, II and I2 and the driving mechanism theremy copending application S. N. 389,650, filed April 21, 1941, now Patent 2,310,720,1ssued Feb. 9, 1943, for Antenna coupling and-tuning system for communication or broadcast receivers and in a copending application of James W. Sharp, S. N. 359,124, filed September 30, 1940, now Patent 2,310,323, for Antenna coupling and tuning system for communication or broadcast receivers, both being assigned the same assignee as the present application.

Briefly, the circuits including the inductances Ill, II and I2 also include an antenna I 6 of low capacity, such as is commonly termed a fish pole antenna, an oscillator circuit (not shown), and a high frequency input circuit to a receiver not shown) including the oscillator. The antenna I6 is connected through an adjustable capacity IT to ground, and through a conductor I8 to one terminal of the adjustable inductance Ill. The other terminal of the adjustable inductance Ill is connected to a terminal of theinductance II, both such terminals being connected to ground through a by-passing condenser I9 of low reactance at the frequencies involved.

The other terminal of the inductance II is connected to the input of the previously mentioned receiver (not shown), and transfers energy from the antenna I 6 through the inductances I0 and II coupled together by the reactance of the condenser I8, into the input of the receiver. grounded, and the other terminal is connected to a point in the previously mentioned oscillating circuit of the receiver so that adjustment of the inductance I2 is effective to adjust the operating frequency of the oscillator, as is common in superheterodyne receivers.

The adjustable inductances II), II and I2 include respectively, powdered iron cores 20, 2| and 22, which are respectively connected to a com-' mon yoke 23 by means of resilient elements 24, 25 and 28, respectively, The electromagnet I3 is suitably connected by a shaft 21 to the yoke 23 to move that yoke away from the inductances Ill, Ii and I2 whenever the electromagnet I3 is energized.

A spring 30 is connected in tension between afixed bracket 3| and the yoke 23, so as to move the yoke 23 as far as possible toward the inductances II), II and I2 whenever the electromagnet I3 is not energized, The yoke 23 is so shaped as to bear against that one of the stops I 4, I5, to which it is nearest, except when the yoke 23 is One terminal of the inductance I2 is moved away from such stops by the electromagnet l3.

The stops H, l are arranged in a turret, being angularly spaced about a common axis and being arranged for rotation about that axis when turned by suitable means, as for example, the hand wheel 32. A shaft 33 is provided at such common axis, and carries a wheel 34, in which internally threaded pinions 35 and 36 are carried. The threaded end of the stops I6 and 5 are respectively screwed into the internally threaded pinions 35 and 36, so that the axial position of each of the stops I4, |5, may be adjusted. Such adjustment is preferablycarried out for each stop when it is in cooperating relation with the yoke 23. The stop I4, as thus illustrated, is prevented from turning by friction with the yoke 23, so that the internally threaded pinion 36 may be turned to adjust the axial position of the stop H, and thereby adjust the position of the yoke 23 and consequently the inductance values of the inductances In, H and I2.

The hand wheel 32 is arranged to turn the shaft 33 through gears 40, and is arranged to energize the electromagnet |3 while one of the stops H, |5 is moving away from the yoke 23 and to maintain the electromagnet l3 thus energized until a succeeding stop comes under the yoke 23. As illustrated, a cam wheel 4| is arranged to close contacts 42 at appropriate times during rotation of the hand wheel 32, thereby completing a cir cult through the energizing coil of the electromagnet l3 and through a suitable source of operating potential 43.

In operation, rotation of the hand wheel 32 from the position shown, begins to move stop I under the yoke 23 and at the same time energizes electromagnet I3 so that yoke 23 and the powdered iron cores 20, 2| and 22 are moved away from the inductances IO, N and i2 to an extreme position. Further rotation of the hand wheel 32 maintains the electromagnet l3 energized, and removes stop I from under the yoke 23 and subsequently moves another stop (not shown) under the yoke 23. When this subsequent stop (not shown) is under the yoke 23, the contacts 42 separate, and deenergize the electromagnet I3 so that the spring 30 quickly moves the yoke '23 back against the stop, thereby positioning the powdered iron cores 20, 2| and 22 in a desired position corresponding to such subsequent stop.

The rapid operation of the yoke 23 away from the stops l4, l5, and particularly back again toward the stops, imposes considerable shock upon the yoke 23 and upon the powdered iron cores 20,

2| and 22. This shock incurred in operation, due

' to the mass of each of the powdered iron cores 'would be extremely undesirable, since it is necessary that the powdered iron cores 20, 2| and 22 be returned to exactly the same position every time a particular stop is under the yoke 23. To this end the resilient elements 24, 25 and 26 are made to have enough stiffness axialLv so that they do not change length during operation.

The resilient elements 24, 25 and 26 are at the same time made so as to have a high degree of resilience transversely, that is, to bending. The necessity for this transverse resilience is clearly seen upon examination of the inductance l0, which is shown in sections. The coiled conductor 50 of the inductance l0 closely surrounds a paper tube or guide 5|, within which the powdered iron core 2|! slides. In order that there be a large inductance change as the iron core 20 slides in or out of the paper guide 5|, the inside diameter of the coiled conductor 50 and the outside diameter of the iron core 20 must differ as little as possible. The paper tube or guide 5| is therefore made of paper as thin as possible consistent with mechanical stiffness and resistance to wear. Furthermore, the iron core 20 is made of as large diameter as possible leaving it free to slide easily within the paper tube 5|. In ordinary broadcast receivers, for example, there ma be allowed only 5 mils clearance between the iron core 20 and the inside of the paper tube 5|.

With such small clearance between the iron core 20 and the wall of the paper tube 5| within which it slides back and forth, it is evident that the driving mechanism which moves the iron core 20 back and forth must not displace it axially with substantial force such as to cause binding. For manufacturing reasons, it is not feasible to constrain the yoke 23 to slide back and forth with sufficient accuracy upon an axis exactly parallel to the axes of the paper tubes 5| and each of the inductances in, II and I2. In fact, manufacturing tolerances must generally be such that the paper tubes or guides 5| within the three inductances III, II and 2 are not even ufficiently near parallel to allow the iron cores 20, 2| and 22 to be driven in parallel lines. Therefore, in order to achieve a desirable large change of inductance of each of the inductances III, II and |2, and

- at the same time to obtain reset accuracy, it is necessary to provide driving means between each of the cores 20, 2| and 22 and the yoke 23 which has substantially no axial resilience but which has considerable transverse resilience.

To this end the resilient elements 24, 25 and 26 are formed of highly resilient wire of any desired shape in cross-section, bein illustrated as round. This wire is wound in a helix, preferably of relativeh' small diameter, and having each pair of adjacent turns of the wire in contact.

By way of example, the structure used in a broadcast receiver where the powdered iron core was one and a half inches long and about onequarter inch in diameter comprises a piano steel wire about fifteen mils in diameter, wound into a helix of about fifty five mils outside diameter. With each adjacent pair of turns in contact, the wire helix is not compressible axially. The wire should be wound so that its resilience normally maintains adjacent turns pressed together with substantial force. It is this force, pressing adjacent turns of the resilient element together, which maintains all adjacent turns of the resilient element in contact at all times except when the axial tension force between the ends of the resilient element is greater than the force between adjacent turns. Even though shock force may momentarily part adjacent turns, the resilient force therebetween immediately causes them to close again; thereby maintaining the overall length of the resilient element constant at all times except during such shock. Reset accuracy of a very high order is thereby attained.

The helical formation of the wire in the resilient element 26, even though adjacent turns are in contact, provides for great transverse resilience, while at the same time maintaining axial length constant. As explained previously, this transverse resilience is of great benefit in allowing the iron cores 20, 2| and 22 to slide freely within the paper tubes or guides 5| of the inductances IO, N

to the yoke 23. The iron core 20 may be molded around'the end of the resilient members 24, 25 and 26, in which case the irregular shape of the external surface of the resilient member provides a good bond between the resilient member and the iron core body. For additional strength in the bond between the iron core and resilient member, the wire at the end of the resilient member may be distorted, if desired. 7

Alternatively, a hole may be drilled axially into one end of one of the iron cores 20. 2| or 22, and the end of resilient members 24, 25, 26 cemented therein. In this case also the irregular outer surface of the resilient member' aids in forming a tight bond between the resilient member and the iron core.

The resilient member 26 is fastened into the yoke 23 by an insulating grommet 52, which is internally threaded to conform to the external surface of the resilient element 26. The grommet 52 may be fastened into the yoke 23 by suitable means, as is illustrated in connection with the grommet 53 which is provided to fasten the resilient element 24 into the yoke 23. The external diameter of one end of the grommet 53 is small, so that it can extend througha hole in the yoke 23, and is externally threaded to receive a nut 54. The grommet 53 is fastened to the resilient element 24 by means of a U-shaped spring 55 whose arms extend through holes on opposite sides of the grommet 53 and bear against the sides of the resilient element 24.

Still another alternative arrangement for fastening one of the resilient elements 24, 25 and 26 to the yoke 23 is illustrated in connection with the resilient element 25. This resilient element 25 extends through a hole in the yoke 23, and is maintained therein by a U-shaped stri 60 of metal, or preferably of resilient insulating material. which extends through a slot 6| in the yoke 23 and presses against the opposite sides of the yoke 23 around the resilient element 25. A hole 62 extends through the yoke 23 andthrough both arms of the U-shaped strip 60, the resilient element 25 being accommodated within this hole. Arms 63 and 64, stamped out of the strip 60 and slightly upturned, bear resiliently against the opposite sides of the resilient element 25 and maintain it fixed in its relation to the yoke 23.

It is generally undesirable to connect the iron cores 20, 2| and 22 to ground, because circulating currents flowing through such circuits including distributed capacities associated with the iron cores would encounter considerable resistance, andundesirably damp the tuned circuits of the receiver. The iron core 20 is insulated from the yoke '23, which is usually grounded, by the insulating grommet 53. Although the grommet 52 associated with the iron core 22 is of insulating material, it is not necessary that it be so, since the inductance I2 is associated with an oscillator, and some small damping of an oscillator circuit ,has little or no effect on its operating frequency. The iron cor 2|, being associated with inductance I I in a tuned amplifier circuit, is desirably insulated from ground, the strip 60 therefore being preferably of insulating material. Of course, if metal be used to form the resilient strip 60, a strip of paper insulation may be provided between the metal strip 60 and the yoke 23 to maintain insulation therebetween, and prevent the core 2| from being grounded.

Where the invention is used in largerapparatus than broadcast receivers, such as in transmitter tuned circuits, the powdered iron core which is to be moved may be of much larger mass. Where such large mass is to be adjusted in posttion, being subjected to shock during such adjustment, the required size of wire to form the resilient element, the resilience element may become unattainable. To provide greater axial stiffness when the resilient element, is under tension, a somewhat different structure'is provided.

In Figure 2 a large powdered iron core I0 is molded around a resilient member H, which is similar to one of the resilient elements 24, 25, 26, except that it is wound around a central, axially disposed, wire I2. The construction and formation of the resilient element II is otherwise the same as that of the resilient elements 24, 25 and 26. At each end of the resilient element II, the external helically coiled wire I3 is fastened to the inner wire I2 by suitable means, Such means may be, for example, by welding or soldering or by suitable mechanical deformation, as by pinching together of th wires. Alternatively, the wire I2 may be bent outwardly and around the end of the coiled helical wire I3, as illustrated in Figure 2. That end of the resilient element II which is embedded in the powdered iron core 10 is made more firm in its bond thereto by distortion of the end 14 of the helically coiled conductor I3, as well as by the previously mentioned bending outwardly of the inner wire 12 around the outer helically coiled wire I3.

The arrangement of Figure 2 has considerable transverse resilience, has as much stiffness in compression as the resilient elements 24, 25 and 26 of Figure l, and has great resistance to tension forces by reason of the tensile strength of the inner wire I2, as well as the resilience of the helically coiled wire I3, which tends to force adjacent turns together.

The helical formation of the wire forming the resilient elements 24, 25, 26 and II is not only of great advantage in providing transverse resilience with great longitudinal stiffness, but also makes for easy individual adjustment of the attached powdered iron cores. That is, for example, the resilient element 24 together with the attached powdered iron core 20, may be turned within the grommet 53, with respect to the yoke 23, and thereby be moved axially with respect to the yoke. Such axial movement of the resilient element 24 and the powdered iron core 20 results when the element is turned, because of the helical, or screw, formation of the resilient element.

The same thing may be done with any of the other illustrated fastenings and resilient elements.

It is to be understood that this invention is especially useful in connecting a driving member, such as the yoke 23, to tuning elements, such ,as the powdered iron cores 20, 2| and 22. It may,

however, be used to provide a driving connection between any sort of driving member and any short of movable piece arranged to move along a guide track or passage. For example, instead from my invention in its broader aspects, and I,

therefore, aim in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of my invention.

I claim:

1. In combination, a powdered iron core, a resilient element aligned substantially axially with said core and having one end afilxed to said core, said resilient element comprising a resilient wire helically coiled so that its adjacent turns press together, whereby substantial axial forces applied to said core through said resilient element do not permanently change the length of said resilient element.

2. In combination, a. powdered iron core, a resilient element aligned substantially axially with said core, said resilient element comprising a resilient wire helically coiled so that its adjacent turns press together, the end of the wire at one end of said resilient element being distorted from said helically coiled formation and being afllxed within said core. whereby substantial axial forces applied to said core through said resilient element do not permanently change the length of said resilient element nor loosen the bond between said resilient element and said core.

3. In combination, a powdered iron core, a transversely resilient element having great longitudinal rigidity aligned substantially axially with said core and having one end affixed to said .core, said resilient element comprising a relatively small resilient wire extending axially of said resilient element and a second resilient wire helically coiled around said first wire so that its adjacent turns press together, whereby substantial axial forces applied to said core through said resilient element do not permanently change the length of said resilient element.

4. In combination, an adjustable inductance comprising a guide passage and a powdered iron core closely fitting within said passage and slidable therein, means for sliding said core within said passage comprising a driven member and a resilient element affixed to said core and to said driven member at spaced points therealong, said driven member moving substantially rectilinearly and substantially in parallel with said passage, said resilient element comprising a resilient wire lielically coiled so that its adjacent turns press together, whereby substantial axial forces applied to said core through said resilient element from said driven member do not permanently change the length of said resilient element and do not cause said core to bind within said passage when said driven member moves in non-parallel relation to said passage.

5. In combination, an adjustable inductance comprising a guide passage and a powdered iron core closely fitting within said passage and slidable therealong, and means for adjusting the position of said core within said passage comprising a driven member and a resilient element affixed at spaced points therealong to said core and said driven member, said resilient element com prising a resilient wire helically coiled so that its adjacent turns press together, whereby substantial axial forces applied to said core through said resilient element do not permanently change the length of said resilient element and non-parallel motion of said driven member with respect to said passage does not cause said core to bind within said passage by reason of the transverse resilience of said resilient element, said resilient element being aflixed to said driven member by means cooperating with the helical groove on the external surface of said resilient member, whereby turning of said core and said resilient member with respect to said driven member is effective to adjust said core within said passage without motion of said driven member.

6. In combination, a plurality of adjustable inductances, each having respectively a. guide passage and a powdered iron core closely fitting therein and slidable therealong, said passages all being substantially parallel and being subject to some non-parallelism, and means for adjusting said cores within said passages in unison comprising a driven member and a plurality of resilient elements, each of said resilient elements comprising a resilient wire helically coiled so that its adjacent turns press together, each of saidresilient elements being afilxed to a respective core and being affixed at a different point to said driven member, whereby substantial axial forces applied to said cores through said resilient elements do not permanently change the length of said resilient elements and whereby non-parallelism between said passages and the path of travel of said driven member is not efiective to cause binding of said cores within said passages.

'7. In combination, a powdered iron core and a resilient element comprising a resilient wire helically coiled so that its adjacent turns press together and form an irregular outer surface, one end of said element being firmly fixed within one end of said core by said irregular surface and said element and core being substantially aligned whereby upon bending of said element the transverse resilience thereof and the firm fixing produced by utilizing the irregular surface prevent loosening between the element and the core or fracture of the core.

8. A tuner for a radio receiver comprising a movable tuning device, spring means tending to move said device in one direction, an electromagnet for moving said tuning device in the opposite direction, spaced stop means, means to bring about cooperation of said spaced stop means with said tuning device in a predetermined order, an adjustable inductance comprising a guide passage, said tuning device compris- 0 ing a powdered iron core closely fitting within said passage and slidable therealong, a core driving member moved in said opposite direction when the electromagnet is energized from a position determined by said stop means, and moved in said one direction by the spring when the electromagnet is deenergized to a position against said stop means, large shock forces being generated at the extreme-ends of movement in said one direction and said opposite direction, a resilient element comprising a resilient wire helically coiled so that its adjacent turns press together and form a screw threaded shape, one end of said element, being firmly fixed within one end of said core by said screw threaded shape and said element and core being substantially aligned whereby upon bending of said element the transverse resilience thereof and the firm fixing Droduced by utilizing the irregular surface prevent loosening between the element and the core or fracture of the core, the other end of said element being joined to said driving member whereby said shock forces applied to said core from said driving member do not permanently change the length of said resilient element and nonparallel motion of said member with respect to v .10 said passaze do not permanently change the Number Name Date length 01' said resilient member and non-parallel 2,240,087 Barrett E Apr. 29, 1941 motion or said member with respect to said pas- 2,299,785 Barrett Oct. 27, 1942 sage does not cause said core to bend within said TEN passage by reason 01' the transverse resilience 5 FOREIGN PA TS of said resilient element. Number Country Date CLARENCE w. WANDRE'Y. 612,408 France July 31, 1926 101,985 Great Britain Nov. 9, 1916 REFERENCES crrEn The following references are of record in the fileot this patent:

UNITED STATES PATENTS Number Name Date 2,226,822 Kirk Dec. 31, 1940 15 OTHER REFERENCES Wireless World, Aug. 31, 1934, page 195. (Copy available in Division 26, Patent Ofifice.) 

